The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of a hybrid powertrain of a vehicle is presented. An engine 102 provides torque to a transmission 104. The transmission 104 transmits torque to a driveline 106. The engine 102 also drives and is driven by a belt alternator starter (BAS) system 110. BAS systems may be characterized by a combination motor/generator used in place of a standard alternator and connected to the crankshaft of the engine 102 via the accessory drive belt.
The BAS 110 converts power from the engine 102 into electrical power, which may be stored in charge storage 112. When the engine 102 is not running, the BAS 110 may use power from the charge storage 112 to drive the crankshaft of the engine 102, and thereby propel the vehicle. The BAS 110 and the engine 102 are controlled by a hybrid engine control module (ECM) 120. The hybrid ECM 120 receives signals from driver inputs 122, such as an accelerator pedal, a gear shift lever, and/or a brake pedal.
When the vehicle comes to a stop, the hybrid ECM 120 may instruct the engine 102 to shut off. For example, this may be achieved by stopping fuel delivery and spark to the engine 102. When the driver desires to start the vehicle from the stop, as indicated by lifting their foot off the brake pedal or pressing the accelerator pedal, the hybrid ECM 120 may command the engine 102 to restart. Also, the engine 102 may be commanded to start by the ECM 120 for reasons not initiated by the driver. When the engine 102 restarts, torque from the engine 102 is transmitted through the transmission 104 to the driveline 106. If the brakes are applied during the engine 102 start, the driveline 106 is unable to rotate, and the torque is transmitted directly to the frame of the vehicle, which is experienced as a jerk disturbance by the driver.